Apparatus for detecting and providing brain signals by use of electroencephalography

Abstract

Apparatus for monitoring a brain signal, especially indicative of muscle fatigue, comprises at least three sensors sensing neuronal activity, wherein one sensor ( 11 ) comprises a reference electrode and the other sensors ( 15, 16 ) comprise sensing electrodes, wherein the reference sensor ( 11 ) serves as a common reference for the other sensors ( 15, 16 ). The reference sensor ( 11 ) is placed within the quadrangle defined by the four positions [F5-F1-C 1-C5] or on a corridor of 10 millimetres width along the line between Fpz to Oz, the first sensing sensor is placed within the quadrangle [C1-C2-P2-P1], and the second sensing sensor is placed within the quadrangle [FT7-FC3-CP3-TP7], with the proviso that the reference electrode is not positioned on the same position as is one of the two sensing sensors and wherein the positions of the sensors delimiting the quadrangles are defined according to the 10-10 Electrode Placement System of the American Clinical Neurophysiology Society.

1 . An apparatus for monitoring a brain signal, especially indicative of muscle fatigue, comprising at least three sensors sensing neuronal activity,
 wherein one sensor comprises a reference electrode and the other sensors comprise sensing electrodes,   wherein the sensor comprising the reference electrode serves as a common reference for the other sensors,   wherein positions of the sensors are defined according to the 10-10 Electrode Placement System (American Clinical Neurophysiology Society, Guideline 5: Guidelines for Standard Electrode Position Nomenclature, 2006),   wherein the first sensing sensor is placed within a quadrangle defined by four positions [C1-C2-P2-P1], and the second sensing sensor is placed within a quadrangle defined by four positions [FT7-FC3-CP3-TP7] and the reference sensor is placed in a position taken from the group comprising a quadrangle defined by four positions [F5-F1-C1-C5] or on the midline as defined by a corridor of up to 15 millimetres width between Fpz to Oz, wherein the positions are chosen with the proviso that the reference electrode is not positioned on the same position as is one of the electrode of the other sensing sensors.   
     
     
         2 . The apparatus according to  claim 1 , further comprising a signal processor, receiving bioelectric sensor signals from the sensors, being connected with the reference electrode and optionally with one or more ground electrodes, and configured to perform a sequence of transformations on the bioelectric sensor signals received from the sensors quantifying an output signal PS lagged , especially on a ratio scale, wherein the transformations include a.) a discrete Fourier transform of the signal time series from the first as well as from the second sensor; b.) a normalization of each of the two Fourier transforms to obtain phase information, insensitive to amplitude information; c.) the calculation of the complex valued cross spectra between the two normalized Fourier transforms; d.) a separation of the lagged components of phase synchronization from the instantaneous components by using the following formula: 
       
         
           
             
               
                 PS 
                 lagged 
               
               = 
               
                 
                   
                     
                       [ 
                       
                         Im 
                          
                         
                           ( 
                           
                             S 
                             
                               xy 
                                
                               
                                   
                               
                                
                               ω 
                             
                             ˇˇ 
                           
                           ) 
                         
                       
                       ] 
                     
                     2 
                   
                   
                     1 
                     - 
                     
                       
                         [ 
                         
                           Re 
                            
                           
                             ( 
                             
                               S 
                               
                                 xy 
                                  
                                 
                                     
                                 
                                  
                                 ω 
                               
                               ˇˇ 
                             
                             ) 
                           
                         
                         ] 
                       
                       2 
                     
                   
                 
                 
                     
                 
               
             
           
         
       
       where S {hacek over (x)}{hacek over (y)}ω  denotes the cross spectra between the two normalized Fourier transforms {hacek over (x)} and {hacek over (y)} at frequency ω, Im denotes the imaginary part, and Re denotes the real part; and e.) providing the resulting value as said output signal PS tagged  as indicative of supra-spinal muscle fatigue. 
     
     
         3 . The apparatus according to  claim 1 , wherein the one or more ground electrodes are attached to either a left or right mastoid, a left or right earlobe, to another part of the specimen's skin or any combination of these. 
     
     
         4 . The apparatus according to  claim 1 , wherein the mounting system of the headset can be a stand-alone holding fixture or can be integrated in a helmet, hat or a textile cap. 
     
     
         5 . The apparatus according to  claim 1 , wherein the apparatus comprises a control unit which is configured to only sense information relating to neuronal signals containing information from a predetermined certain frequency range, especially from one, two or three elements of frequency ranges of the group of frequency ranges consisting of the frequency range between 7 and 13 Hz, of the frequency range between 3 and 7 Hz, of the frequency range between 13 and 20 Hz. 
     
     
         6 . The apparatus according to  claim 1 , wherein the control unit is configured to detect said neuronal signal at a sampling rate of 250 Hz and with 24 bit precision. 
     
     
         7 . The apparatus according to  claim 1 , further comprising storage means for storing neuronal signals. 
     
     
         8 . The apparatus according to  claim 1 , further comprising an output unit to output the neuronal signal in real-time. 
     
     
         9 . The apparatus according to  claim 8 , wherein the output unit is from the group comprising a display, a loudspeaker or a vibrator to be attached to the user or the cap, hat or helmet. 
     
     
         10 . The apparatus according to  claim 9 , wherein said neuronal signal is transported to a visual display unit mounted within a user's field of view, or to a visual display unit contained in a mobile device running on Android, Windows Mobile, or iOS, or to a visual display unit contained in another sports monitoring device. 
     
     
         11 . The apparatus according to  claim 1 , wherein the reference sensor is placed on the midline of the scalp, as defined by a corridor of up to 10 millimetres width between Fpz to Oz. 
     
     
         12 . An apparatus for monitoring a brain signal, especially indicative of muscle fatigue, comprising at least three sensors sensing neuronal activity,
 wherein one sensor comprises a reference electrode and the other sensors comprise sensing electrodes,   wherein the sensor comprising the reference electrode serves as a common reference for the other sensors,   wherein positions of the sensors are defined according to the 10-10 Electrode Placement System (American Clinical Neurophysiology Society, Guideline 5: Guidelines for Standard Electrode Position Nomenclature, 2006),   wherein the first sensing sensor is placed within a quadrangle defined by four positions [C1-C2-P2-P1], and the second sensing sensor is placed within a quadrangle defined by four positions [FC4-FT8-TP8-CP4], and the reference sensor is placed in a position taken from the group comprising a quadrangle defined by four positions [F2-F6-C6-C2] or on the midline as defined by a corridor of up to 15 millimetres width between Fpz to Oz, wherein the positions are chosen with the proviso that the reference electrode is not positioned on the same position as is one of the electrodes of the other sensing sensors.   
     
     
         13 . The apparatus according to  claim 12 , further comprising a signal processor, receiving bioelectric sensor signals from the sensors, being connected with the reference electrode and optionally with one or more ground electrodes, and configured to perform a sequence of transformations on the bioelectric sensor signals received from the sensors quantifying an output signal PS lagged , especially on a ratio scale, wherein the transformations include a.) a discrete Fourier transform of the signal time series from the first as well as from the second sensor; b.) a normalization of each of the two Fourier transforms to obtain phase information, insensitive to amplitude information; c.) the calculation of the complex valued cross spectra between the two normalized Fourier transforms; d.) a separation of the lagged components of phase synchronization from the instantaneous components by using the following formula: 
       
         
           
             
               
                 PS 
                 lagged 
               
               = 
               
                 
                   
                     
                       [ 
                       
                         Im 
                          
                         
                           ( 
                           
                             S 
                             
                               xy 
                                
                               
                                   
                               
                                
                               ω 
                             
                             ˇˇ 
                           
                           ) 
                         
                       
                       ] 
                     
                     2 
                   
                   
                     1 
                     - 
                     
                       
                         [ 
                         
                           Re 
                            
                           
                             ( 
                             
                               S 
                               
                                 xy 
                                  
                                 
                                     
                                 
                                  
                                 ω 
                               
                               ˇˇ 
                             
                             ) 
                           
                         
                         ] 
                       
                       2 
                     
                   
                 
                 
                     
                 
               
             
           
         
       
       where S {hacek over (x)}{hacek over (y)}ω  denotes the cross spectra between the two normalized Fourier transforms {hacek over (x)} and {hacek over (y)} at frequency ω, Im denotes the imaginary part, and Re denotes the real part; and e.) providing the resulting value as said output signal PS lagged  as indicative of supra-spinal muscle fatigue. 
     
     
         14 . The apparatus according to  claim 12 , wherein the one or more ground electrodes are attached to either a left or right mastoid, a left or right earlobe, to another part of the specimen's skin or any combination of these. 
     
     
         15 . The apparatus according to  claim 12 , wherein the mounting system of the headset can be a stand-alone holding fixture or can be integrated in a helmet, hat or a textile cap. 
     
     
         16 . The apparatus according to  claim 12 , wherein the apparatus comprises a control unit which is configured to only sense information relating to neuronal signals containing information from a predetermined certain frequency range, especially from one, two or three elements of frequency ranges of the group of frequency ranges consisting of the frequency range between 7 and 13 Hz, of the frequency range between 3 and 7 Hz, of the frequency range between 13 and 20 Hz. 
     
     
         17 . The apparatus according to  claim 12 , further comprising an output unit to output the neuronal signal in real-time. 
     
     
         18 . The apparatus according to  claim 17 , wherein the output unit is from the group comprising a display, a loudspeaker or a vibrator to be attached to the user or the cap, hat or helmet. 
     
     
         19 . The apparatus according to  claim 18 , wherein said neuronal signal is transported to a visual display unit mounted within a user's field of view, or to a visual display unit contained in a mobile device running on Android, Windows Mobile, or iOS, or to a visual display unit contained in another sports monitoring device. 
     
     
         20 . The apparatus according to  claim 12 , wherein the reference sensor is placed on the midline of the scalp, as defined by a corridor of up to 10 millimetres width between Fpz to Oz.